Manchester United defender Phil Jones is also recovering well from a shoulder injury and the England boss hopes he will be involved before the squad return home.

He told a press conference broadcast on Sky Sports News:"The first three days have gone as well as I could possibly have hoped for. But there's a long way to go and three more days to get through but we've made a good start.

"We had a slightly unfortunate incident with John Stones. He twisted his knee very slightly in training but it's nothing serious.

"He could have trained but we decided to leave him out because it's so early on and we don't want to take any risks.

"It was nice to see Phil Jones joining in the warm-up. He's training very very well and it looks like he might be taking part even before the end of this week."

Hodgson feels the competition for places in the squad, which will be reduced to a confirmed final 23 before England head to Brazil, has ensured the players take their training especially seriously.

But while relaxation is not an option, he insists he is leading a "happy" camp.

"We don't talk about relaxation, or about sessions being light-hearted or serious, we talk about the job that we need to do and we expect that every time the players go onto the training ground that they are 100 per cent following what we think needs to be done."Roy Hodgson

"If they happen to enjoy it then that's a major bonus but we don't set out to make it enjoyable, we set out to do the work that we think is absolutely necessary if we're to have any success at this World Cup."

Hodgson made some tough calls before revealing his first selection - his decision to include Southampton teenager Luke Shaw instead of veteran left-back Ashley Cole was hotly debated.

He believes that fierce scrap for places on the plane has helped focus his players' minds sharply on the task in hand.

"I think they're excited to be selected and I think everyone realises that my choice was a difficult one," Hodgson added.

"It wasn't just a case of taking the only players that were there, there were more players than these who could easily have come so I think there was a lot of tension among players before I made my selection as they waited to be chosen.

"So in this camp of course there's a lot of enthusiasm but they're also happy that they are taking part in this incredible adventure and that they're the ones who are going to be leading England over the next few weeks."

Wayne Rooney, who at the age of 18 broke on to the international scene with four goals at the 2004 European Championships, has failed to impress at the last two World Cups.

Big things are expected from the Manchester United striker in South America, but should he flounder at the tournament then Hodgson insists it will not be "for the want of trying".

He said: "He knows what a good player he is, he knows the eyes, certainly of England, if not the rest of the world, are going to be on him and he'll do everything he can to make certain he brings out his best qualities.

"He spent his week off here in Portugal and he trained during that time. He said to me, 'When you arrive on Monday, I'll meet you there and I want to be 100 per cent ready to train from the first day'.

"He's a bit disappointed because I decided to leave him out of the exercise I was doing, which involved a lot of shooting, because I wanted to protect his thigh.

"If it had been up to him, he'd have been in it having as many shots as all the others."